The invention relates to a bearing seal, especially for roller bearings, which revolve at high rotational speeds and contain a lubricant, such as an oil or a grease.
The bearings are constructed with bearing seals with respect to the sealing of inner bearing rings, revolving at high rotational speeds and divided into two spaces, separated by a bearing seal, one containing a lubricant, and the other free of the lubricant.
According to U.S. Pat. No. 3,915,519, the shaft, mounted in a friction bearing, has rotational direction-dependent spiral-shaped conveying grooves for the lubricant. These grooves can convey the lubricant into the interior of the bearing. As a result, for the mounting, a hydrodynamic overpressure develops within the friction bearing and, for sealing the bearing, the lubricant constantly is conveyed back into the bearing.
Likewise, a bearing seal, with a sealing edge, revolving by sliding and lying circumferentially on an inner bearing ring, forms at a circular elastic sealing lip, which separates a part, such as a gearing, which is driven along a rotating inner bearing ring filled with oil or grease, and a lubricant-free part, a system with a roller bearing with a roller bearing cage, which is open at one side. Due to the movement of the roller bearing, the lubricant in the bearing is pressed out in the direction of the open side of the roller bearing and spiral flutes, formed depending on the direction of rotation, and convey the lubricant back into the bearing cage and to the sealing edge. Due to the conveying force of the spiral flutes, a local hydrodynamic overpressure of the lubricant may arise in the region of the sealing edge against the pre-stress of the latter, produced by the elastic sealing lip. As a result, the pre-stress of the sealing edge is overcome and consequently a leak of the lubricant develops between the sealing edge and the inner bearing ring.
According to the DE 4215905A1, the sealing lip has radial, spiral knobs at the side of lubricant-containing space. These knobs form a radial, helical path with helical grooves lying in between. Due to the high rotational speed of the inner bearing ring the lubricant is forced hydrodynamically away from an inner radial sealing gap in the direction of an outer bearing ring.
The primary object of the invention is to provide a simple bearing seal for a bearing, which effects good sealing, as well as adequate lubrication of the bearing, possible even at the high rotational speeds.
Essentially, in the case of a bearing seal, extending between an outer bearing ring and an inner bearing ring, and arranged so that it can rotate about the bearing axis, it has an elastic sealing lip, which slides circumferentially relative to the lubricant space. The surface of the sealing lip facing the lubricant space has radial, helical paths disposed between projecting members, which in the installed state extend circumferentially from the surface of the inner bearing ring. By these means, adequate lubrication at the sealing lip, as well as adequate tightness even at high rotational speeds, is assured.
Advantageously, the height of the projecting members in the axial direction of the bearing increases radially towards the outside. As a result, the conveying of the lubricant is increased further without any decrease in the sealing effect.
Further, to ensure the service life of the sealing edge, the surface of the inner bearing ring contacting the sealing lip has a surface of high quality with respect to smoothness.
Examples of the invention are described in greater detail in the following with reference to the drawing, in which: